OBJECTIVES: Radiation sensitization of cell killing and of mutagenesis by combined treatment of S. typhimurium TM677 with radiation and electron affinic radiation sensitizers and antitumor drugs is to be characterized. DNA damage by these combined treatments is to be assayed, e.g., by strand break analysis. METHODS: Survival curve analysis following combined treatment of cells in aqueous suspension by radiation and various sensitizers/drugs is compared with mutagenesis caused by these same treatments. The effect of oxygen on these endpoints is examined by treating cells in N2-and O2-saturated suspensions. DNA damage is evaluated by agarose gel electrophoresis and thymine residue release studies. RESULTS: To date, the TM677 mutationa assay to 8-azaguanine resistance is charactherized for the effects of methyl methanesulfonate and N-methyl-N'-nitro-N-nitorsoguanidine. These agents are increased ca. 2-fold in effectiveness when presnt with cells under conditions of shift-up in growth rate.